docs: def _include_term(self, term):
          """Add a single term to the current ontology.
  
          It is needed to dereference any term in the term's relationship
          and then to build the reference again to make sure the other
          terms referenced in the term's relations are the one contained
          in the ontology (to make sure changes to one term in the ontology
          will be applied to every other term related to that term).
          """
          ref_needed = False
  
          if term.relations:
  
              for k,v in six.iteritems(term.relations):
                  for i,t in enumerate(v):
  
                      #if isinstance(t, Term):
                      try:
  
                          if t.id not in self:
                              self._include_term(t)
  
                          v[i] = t.id
  
                      except AttributeError:
                          pass
  
                      ref_needed = True
  
          self.terms[term.id] = term
          return ref_needed